Machine for grinding and polishing optical lenses, spectacle glasses, and the like



April 25, 1933. I J. DESENB ERG 1,906,050

' MACHINE FOR GRINDING AND POLISHING OPTICAL LENSES,

' SPECTAOLE GLASSES, AND THE LIKE Filed'April 15, 1929 3.Sheets-Sheet l747 22 Jo T1114! 0 I 5mm n-Yoz 1 jaw/i650? Zerg J. 'DESENBERG 1,906,050NDI'NG AND POLISHING OPTIC-AL LENSES,

CLE ES AND THE LIKE Filed 15, 1929 s Sheets-Sheet 2 GLASS April April25, 1933.

MACHINE FOR GRI SPECTA Umm/mIg/u Z fare/Jew ery sushi-u. H mm April1933. J. DESEN BERG MACHINE FOR GRINDING AND POLISHING OPTICAL LENS'E 3Sheets-Sheet 3 iled April 15, 1929' U/wvmko/cz 1 0367 265872 eryPatented Apr. 25, 1933 I UNITE-D STATES PATENT OFFICE JOSEF DEGENBERG,OF COLOGNE, GERMANY MACHINE FOB GRINDING POLISHING OPTICAL LENSES,SIPECTACLE GLASSES, AND

THE LIKE I Application filed April 15, 1929, Serial No.

The invention relates to a machine for grinding and polishing opticallenses, spectacle glasses, and the like which is so con-- structed as tobe capable of producing automatically a product which is absolutelyuniform in an optical sense. The principle underlying the operation ofthe machine is that the glass elements forming the work passintermittently in succession through a series of operatingstations whichare arranged concentrically to a rotary head ad-' justable in uniformangular steps, each station comprising a grinding tool having thedesired spherical surface and rotating about the axis thereof and a workcarrier co-operating alternately in pairs with these grinding tools. l

In the known lens grinding machines, the grinding tools consisting asusual of soft metal shaped on their working surfaces according to thespherical surface to be produced by the grinding operation are movablyand freely connected with their driving axis of rotation so that duringthe grinding operation they bear on the shaped surface of the workitself. This arrangement which is also usual in most of the handactuated lens grinding ap aratus has the disadvantage that the sur ace,of the grinding tool "which determines the grinding shape continuallyalters owing to the more or less non-uniform wear caused by the roughgrinding material. The ground surface of the Work is also obviouslymodified correspondingly, and therefore a definite desired surface canonly be obtained by constantly supervising the progress of the wear sothat the grinding operation can be interrupted when the desired shape.is attained. The continual alteration'in shape of the grinding tool canonly be compensated by frequently exchanging and reconditioning thetool, thereby excluding theoretically and practi cally automaticoperation of the machine in the sense of producing a uniform product ofmanufacture having predetermined optical properties without supervisingindividual grindin operations.

In the machine which forms the subject of the invention theaforesaidhindrance to 355,280, and in Germany April 17, 1923.

oscillations to one of the two temporarily I co-acting elements about atransverse axis which passes through the centre of curvature of thesurface to beproduced and the axisof'rotation of the other element orfor the" urpose of obtaining special corrective resu ts through a pointlocated at an accuratelycalculable small distance from said centre ofcurvature, and also as before through the axis of rotation of the otherelement. 7

The necessary grinding pressure is produced by causing the element whichis not adapted to carry out a transverse oscillatory movement to beyieldingly pressed upwards in an axial direction against the oscillating1 element. This pressure may be produced by a weighted lever and canobviously be acin relation to the axis thereof. The nonoscillatingelements of the individual stations mechanically rotated about theoptical axes of the surfaces to be worked are pref- Figure 3 is asectional plan on the line III-III of Figure 1 of part of the machine.

Figure 4 is a vertical section on the line IV--IV of- Figure 1 of a partof the machine.

Figure 5 is a vertical section on the lines VV of Figure 1.

Figure 6 shows diagrammatically partly in elevation and partly insection the main features of a modification of the invention in whichthe rotary grinding spindles are arranged horizontally.

Figure 7 is a plan view corresponding to Fi ure 6.

he baseplate 1 of the machine carries centrally a vertical cylindricalcolumn 2 provided with a flange 3 by which the column is secured byscrews 4 to the base plate. A hollow shaft 5 embraces the column and isrotatably supported at its lower end on a foot bearing ring 6, which isnon-rotatably connected by a screw 7 with the column 2. The upper end ofthis hollow shaft carries a bell-shaped rotary head 8 non-rotatablyconnected therewith and provided with a number of horizontal oscillatoryaxes 10 radially disposed relatively to the axis of rotation of therotaryhead and angularly equi-distant from one another. The inner endsof the oscillatory axes are carried in ball bearings 11 lodged in thewall of the hollow shaft 5. On the outer end of each of the oscillatoryaxes is secured a boss 13 and oscillatory arm 14. The boss 13 issupported by a ball bearing 12 mounted in the cylindrical wall of therotary head. The arm 14 carries a guide 15 having its path of movementextending vertically to the oscillatory axis. A slide 17 is mounted inthe guide and is adjustable therein on both sides of the oscillatoryaxis by means of a screw spindle 16. The slide 17 carries in acylindrical hole parallel to the guide 15 an exchangeable and passivelyrotatable work holder 19 on the lower end of which the work 20 formedfor example by a convex-concave lens is arranged. The work 20 is heldagainst the end face of the work holder by the co-operation of a suctionbox 21 which in known manner is placed under vacuum. The suction box isconnected by a canal 23 extending through the work holder 19 and anupper retaining cap 22 therefor with an adjacent pipe 24 whichcommunicates with a suitable air suction pump.

A toothed sector 25 is secured on each of the oscillatory axes 10 in theinterior of the rotary head and engages with a similar sector 27supported on a pin 26 on the inside of the head. This sector 27. carriesa cam roller 30 on a lateral arm 29 capable of oscillation in an axialplane radial to the pin 26 about a pivot 28. The roller 30 is normallycaused to'engage in a groove 32 of a cam drum 33 by means of a platespring 31 acting on the lateral arm 29. The drum 33 is supported on aframehead 35 by means of an annular flange 34 arranged on the upper endof the drum and by its inner cylindrical surface bearing againstappropriate surfaces on the framehead 35 which is secured by means oftwo columns 36 to the base plate so as to be co-axially mounted with thecolumn 2 and rotary head 8. The cam drum is prevented from longitudinalmovement in the upward direction by an annular plate 37, and is providedat its lower edge with a toothed crown 38 engaging with a driving wheel39 rotating around a pivot pin 40 secured to the side of the head 35.The boss of the driving wheel 39 carries a chain wheel 41 connected by achain 42 to a chain wheel 43 of an electric motor 44 by which it isdriven. The motor 44 is mount-ed on a lateral bracket 45 of one of thecolumns, 36.

In the region of the lower end of each of the Work holders 19 a grindingtool 46 made of suitable metal or the like is exchangeably secured tothe upper end of a spindle 47 which extends longitudinally through ahollow spindle 48 parallel to the axis of rotation of the rotary head.The spindle 47 is non-rotatably connected with the spindle 48 asindicated by the spring bar 49 but is capable however of longitudinaladjustment in the spindle 48. The hollow spindle is supported "at itsupper end by means of a ball bearing 50 in a bearing block 51 secured bymeans of screw bolts 52 to an annular platform 53 carried by the casing54 of the machine. The lower end of the hollow spindle is supported in aball bearing 55 which is mounted in an inwardly directed annularprojection 56 of the casing 54 by means of a screw plug 57. A cordpulley 58 is secured to each hollow spindle and can be driven in commonwith other pulleys by a cord 59 driven by a motor (not illustrated) inorder to impart the necessary drive to the tool spindle 47 and thegrinding tool 46. The lower end of each of the spindles 47 is connectedwith a cross beam 66 so as to be immovable in the longitudinal directionrelatively thereto by means of a channel bearing held in position by ascrew cap 60. The cross beam 66 is mounted on the upper end of apressure rod 67 adjustable longitudinally and guided at its lower end ina block 68. A pin 70 is rotatably mounted in a horizontal axis in theforked end of a lateral arm of the block 68. A compensating lever 71 isoscillatably carried by the pin 70 and consists of two bars connected inparallel so as to leave an intermediate space. This compensating leveris loaded at its inner end by a counterweight 72 and at its outer endengages an adjusting collar by means of a fork 73 and two lateral pins74. The collar 75 is longitudinally movable on the rod 67 and can be setin an adjusted position by means of a pressure screw 76. The transversemember 66 carries a collecting vessel 78 by means of two columns 77longitudinally movable the machine. The upper end of the collectingvessel or receiver 78 surrounds the grinding zone during the grinding oeration and serves to receive the particles ung off during the grindingoperation. The receiver is made annular for the purpose of allowing thepassage of the spindle 47.

Whilst the grinding tool 46 is rapidl rotated by means of its spindle 47-throug the medium of the pulley 58 and spindle 48 it is pressed by thecounter balance lever 71 with the desired grinding pressure against thecontacting surface of the work 20 which is being operated on. As throughthe medium of the drum 33 constantly being rotated by the motor 44 andthe intermediate action of the two toothed sectors 25 and 27, the workholder 19 is moved to and fro parallel to a vertical plane passing tothe platform 33. A feeler or lever 83 is.

movablyarranged on a lateral arm 82 of the standard so that its point,preferably consisting of a diamond is disposed in the vicinity of theupper surface of the grinding tool 46. A contact-maklng member 84 isarranged adjacent the opposite arm of the lever 83, and its terminal isconnected by a wire conductor 85 passing downwards through the interiorof the standard 81 to the winding of a magnet c011 86, wh1ch by means ofan angle racket 87 1s fixedly mounted on the lower annular pro]ect1on 56of the casing 54. The movable magnet core 88 of this coil is provided ona swinging lever 89 rotatable about a pin 90 carried by the casing. Thelower inwardly directed end of said lever lies adjacent an inclinedabutment surface 91 provided on top of the transverse member 66. Theproportions and co-operation of the parts are such grinding action onthe work concerned is interrupted. I

A further arrangement for avoidin any undesired grinding action isprovided and adapted to come into operation when the work carried by theholder 19 concerned breaks or slips out or even when the holder has notbeen fed with work. Forthis purpose a suction cylinder 92 is secured tothe lower edge of the rotary head .at each operating station. The pistonrod 94 of a piston 93 movable within the cylinder is loaded at its lowerfree end witha weight 95. The upper closed end of the cylindercommunicates by a connection '96 with the suction pipe 24 connected tothe suction box .of the associated work holder 19 and com- -municatingthrough the medium of a throttle 97 provided below the connection 96with the pum producing the necessary vacuum. In the ine of movement ofthe weight 95 and below the suction cylinder is dis-' posed a'lateralarm 98 of a supporting lever- 99 which oscillates about a pin 100secured to the casing. The end of the lever 99 which is forked asindicated at 10l'can beset in the path of the adjusting bush 75 securedto the rod 67. When'owing to breakage or absence of the work the suctionbox of the associated work holder is not closed to atmosphere, thepiston 93 which under effective vacuum is normally held in its upperposition moves downwards under the load of the weight 95 and contactswith the lateral arm 98 causing the supporting lever 99 to oscillate sothat its forked end 101 moves in the path of the adjusting collar 75 and7 thereby preventing the undesired upward movement of the pressure rodof the grinding spindle and grinding tool. By these means in such casesthe destruction of the grinding surfaces is avoided.

A motor 102 mounted on a bracket surface 103 of the casing 54 serves forthe intermittent rotation of the rotary head by which the work elementsare brought in succession to the different operating stations. A worm104 is provided on the motor shaft and drives a worm wheel 105' of acounter shaft which in turn through the medium of a worm 106 drives asecond worm wheel 107 causing a control shaft 108 'to rotate at a slowspeed in accordance with the desired duration of the individualoperative periods.

toothed crown 116 secured to or formed on the lower end of the hollowshaft 5.

In order to clear the path of movement for the tool holder and the workcarried thereby during this intermittent movement of the rotary head, areturn device is pro vided which is actuated by a cam 117 mounted on thecontrol shaft 108. This cam acts for a certain period of its rotationthrough the medium of a roller 118 on a rod 119 which is guided in anarm 120 on the cas ing 54 and which is connected at its u per end to alever 121 mounted on the ax e supporting the counter-balance lever 71.Theseaxles 70 are connected by universal joints 122 or similar means insuch a manner that they rotate together. The boss of a lift arm 160non-rotatably connected with the axle 70 is arranged between the twobars of each compensating lever 71, and at its end located below theloaded arm of the latter is provided lateral projections 161 so thatwithout interfering with the ordinary free oscillating movement of thelever 71 they are capable upon sufiicient upward movement of contactingtherewith. By the action of the lever 121 and the cam 117 all thecounterweighted levers are therefore so moved in unison that by means ofthe pressure rods 67 ,the associated grinding spindles and tools andalso through the medium of the cross members 66 and the columns 77, thecollecting containers 78 are moved down to such an extent that they passout of the region of rotation of the lower ends of the work holders 19.

In order to determine accurately the angular position of the rotary headin the individual operating stations, the head is provided near itslower edge with appropriately spaced apertures 123 in which a pin 124engages. This pin is movably arranged in a ra ial direction in a guidebush 126 carried by a part 125 of the casing 54 and is adapted to bebrought out of engagement against the action of a spring 128 by means ofa bell crank lever 127 pivotally mounted in the part 125.

For this purpose the horizontal arm of the bell crank lever 127 isconnected with a pressure rod 129 carrying at its lower end beneath thearm 120 a roller 130 coactiug with a cam 131 mounted on the controlshaft 108. The cam on this shaft is so constructed that before thecommencement of an angular movement of the Maltese cross 111, the cam131 lifts the roller 130 and thereby retracts the pin 124 from itsengagement position in the hole 123 concerned.

In order to provide for cleaning the work and the work holders betweentwo successive grinding operations for the purpose of removing adherentcoarse grinding material the rotary head is' not moved from station tostation in a single step but in two steps so that in the intermediateposition the work can be subjected to the actlon of a washing or rinsingdevice. For this purpose washing tanks 132 are arranged between theoperating stations. Each of the tanks is carried by a column 133supported by the transverse member 66 of the adjacent grinding spindlein the direction of movement, each column 133 participatin in themovement of the transverse mem er and being ided vertically in thecasing 54 as indicated at 134. The washing tank is open at the top andis supported at such a height that during the upward movement which itmakes with the transverse beam the lower end of the work holder isimmersed in the water contained in the tank. The tanks are each fed byan inlet pipe 135 and are provided with an outlet pipe 136, the upperend of which ensures uniformity in the height of the rinsing fluid.Owing to the oscillatory movement which the work holders undergocontinually during the operation as hereinbefore described, andtherefore also during the rinsing periods the cleaning action of thewashing fluid is very much enhanced so that the grinding residues areremoved with certainty from the work and tool holders.

In order to remove the finished work from the ends of the tool holdersand to exchange it for new work to be operated on, a feed table 137 isprovided in place of a grinding spindle at a position on the machinewhere the exchange is effected. The table 137 can be operated about avertical shaft 138. Centering abutments 139 and 140 are provided nearthe circumference of the surface of this feed table and at appropriateradial distances from its axis in the receiving position of the workholders. For example four of such abutments are provided displaced 90with respect to one another, and are yieldingly arranged in airs onplate springs 141. The feed table 137 is moved downward before thecommencement of each intermittent rotary movement by being connected,for example, with one of the cross beams 66 or by other suitableauxiliary means, and is then rotated through a right angle. In thesucceeding upward movement one of the four receiving positionsapproaches the end of the work holder temporarily directed towards thereceiving device into this co-axial movement.

During the first approaching movement to the work holders the action ofthe suction air holding the work against the ,work holder is temporarilyrelieved, for example, by automatically opening an air valve (notillustrated) so as to allow the work to be released from the workholderand deposited on the feed table. In the meanwhile the succeedingreceiving station of the feed table rotating in the direction of thearrow 142"has been supplied with fresh work which is lifted by'thesucceeding intermittent rotation of the feed table against the emptytoolholder. Hereupon the suction action on this tool holder is restoredso that the work is securely held in its correct position on the undersurface of the holder, and in the succeeding downward movement of thereceiving table is taken therefrom. The work to'be operated on in themachine may be placed on the receiving position of the feed table andremoved therefrom in a finished condition either by the hand of theoperator or by anysuitable automatic device replacing this handmanipulation.

The work supplied to the work holders of the machine in this manner isconveyed during the intermittent rotation of the rotary head of themachine in the direction of the arrow 142, Figure 2, through the wholeseries of operating stations. Suitably different positions and the workis subjected first of all to a'coarse grinding action, then to finegrinding and finally, for example, at the last four stations topolishing. Between each station as previously described the work isimmersed in a rinsing tank in which the grinding material remaining fromthe operation carried out at the previous station is removed.

In order to be able to carry out the polishing operation efiectively itis necessary or at least preferable not to allow the tool to actuniformly over the entire surface of the work, but to'increase or reducethe effective pressure alternately at the inner and outer zone of thissurface. This is attained in the machine by slightly altering theeffective distance of the work holder from the oscillatory axis thereofat the different stations where polishing occurs by shifting italternately to both sides of the centre of curvature of the surface tobe polished.

For this purpose and as indicated in the drawings a toothed wheel 144 isarranged on the upper end of each of the screw spindles Y 16 above theguides 15. Pawls 145.01' 146 are so, arranged at certain distances infront of the operating station on arms 147 secured to the platform 53,that these wheels 144 enter into rotary engagement during theintermittent rotary movement alternately with one of the inner pawls 145and one of the outer pawls 146. The adjustment is so determined that theangular movement of the wheels thereby produced in the reverse directionis the same, so that before the finished work is deposited the correctmean oscillating position of the work holder 19 is attained.

A rinsing tank constructed as hereinbefore described ispreferablyarranged between the last polishing station and the delivery table forthe purpose'of removing the polishing residue before the finished workis deposited on the table.

In the modification ofthe machine diagrammatically illustrated inFigures 6 and 7 the grinding axes of the different operating stationsare radially arranged relatively to the shaft 149 of the rotary head 150mounted centrally of the base plate 148. The work arms and iscontinually rotated by any desired motor power so that by co-operationof springs 155 the pivoted arms are caused to carry out an uninterruptedup and down movement. The grinding spindles 156 are so arranged radiallyto the rotary head that at each operatingstation the middle plane ofoscillation of the pivoted arm or the work carrier coincides with thevertical plane'through the axis of rotation of these grinding spindles.Each grinding spindle isalso longitudinally adjustable in a hollow axle157 which is supported in a bearing 158 mounted on the outer part of thebase plate 148 and which carries a driving pulley 159 effecting therotation of the grinding spindle. The necessary grinding pressure isproduced by means of weight-loaded bell crank levers or the like whichtend to move the grinding'spindles inwardly in a radial direction andwhich are controlled b suitable means so that before each intermittentmotion of the rotary head, said spindles may be withdrawn from theoperative posltlon and thereafter returned.

I claim: 1. A machine for grinding lenses in which the work is subjectto coarse grinding, fine grinding and polishing at successive stationsarranged in a circular series, the combination of grinding toolsrotatably mountved at the-respective stations and having the desiredsurface of curvature, a rotary head, work holders,supports for saidworkholders, pivotally mounted on said rotary head to permit theoscillationof said work holders about points on the axis of saidrespective tools at approximately the centers of curvature of thesurface to be ground, and means for intermittently rotating said headfor moving said work holders from station bination of a rotary head, aseries of hollow spindles arranged around said head, means for rotatingsaid spindles, shaft-s adjustably and yieldably supported 1n sald.spindles, and adapted to be rotated thereby, grinding tools carried bysaid shafts, work: holders pivotally mounted on said head and sosupported and arranged as to permit their oscillation about pointslocated on the axes of the spindles at approximately the centers ofcurvature of the surfaces to be ground and means for intermittentlyrotating said head to move said work and holders from station tostation.

4. In a lens grinding machine, a longitudinally movable rotary shaft, agrinding tool mounted at one end of the shaft, means for feeding thetool to the Work during grinding, said means consisting of a movablethrust bcaring for said shaft, a Weighted lever connected to saidbearing and means for automatically stopping the feeding at apredetermined point, said last named means consisting of a feeleradapted to be engaged by the grinding surface of said tool. an obstaclemoved into the path of feed and electrical operating means for saidobstacle controlled by said feeler.

5. The machine claimed in claim 3 wherein means is provided fortemporarily retracting the grinding tools as the work holders are movedfrom station to station.

6. The machine claimed in claim 3 wherein washing tanks are locatedbetween adjacent stations and means is provided for automaticallydipping said holders and work carried thereby into said tanks as saidholders and work are moved from station to station.

7. A machine for grinding lenses in which the work is subject to coarsegrinding, fine grinding and polishing at successive stations arranged ina circular series, two groups of cooperating elements, consistinrespectively of grinding tools and Work holders, the elements of onegroup being rotatably mounted at the respective stations, a rotary head,supports for the elements of the other group pivotally mounted on saidrotary head to permit oscillation of the elements of said other groupabout points on the axis of rotation of the elements of said one groupat approximately the centers of curvature of the surfaces to be ground,and means for intermittently rotating said head for moving the elementsof said other group from station to station.

8. The machine claimed in claim 7 wherein means is provided foradjusting the supports so as to permit the radii of oscillation to bevaried.

the combination of grinding tools rotatably mounted at the respectivestations and having the desired surface of curvature, a rotary head,oscillating work holders carried by said head, means for oscillatingsaid work holders and means for intermittently rotating said head formoving said work holders from station to station.

10. The machine claimed in claim 9 wherein means is provided forautomatically adjusting the work holders so as to permit the radii ofoscillation to be varied from any station to any other station.

11. In a machine for grinding lenses in which the work is subject tocoarse grinding, fine grinding and polishing at successive stationsarranged in a circular series, the combination of grinding toolsrotatably mounted at the respective stations, a rotary head, lensholders carried by said head. a rotary cam, connections between saidhead and cam for oscillating said lens holders during grinding and meansfor intermlttent- 1y rotating said head to move said lens holders fromstation to station.

12. In a machine for grinding lenses in which the work is subject tocoarse grinding, fine grinding and polishing at succes sive stationsarranged in a circular series, the combination of grinding toolsrotatably mounted at the respective stations, a rotary head mountedinside said circular series, lens holders carried by said head, a rotarycam concentricwith said head, connections between said head and cam foroscillating said lens holders during grinding and means forintermittently rotating said head to move said lens holders from stationto station.

13. In a machine for grinding lenses, cooperating elements comprising acircular series of work holders and a circular series of grinding tools,a rotary head for supporting the elements of one of said series, arotary cam arranged concentric with said head, connections between saidcam and the elements of one of said series for oscillating said lastnamed elements, means for rotating the elements of the other said seriesand means for intermittently rotating said head so as to bring each ofthe elements of the series carried thereby into successive positions tocooperate successively with the elements of said other series.

14. An automatic lens grinding machine comprising a rotary grindingtool, a suction lens holder, a source of suction therefor, means forminga suction passage between said source and holders and means located insaid passage and operative at predetermined increase in the pressuretherein and means controlled by the operation of said last named meansfor preventing continued grinding.

15. In a machine for grinding lenses in which the work is subject tocoarse grinding,

fine grinding and polishing at successive stations arranged in acircular series, a combination of grinding tools mounted at therespective stations, a rotary head, lens holders carried by said head, acommon means for turning said lens holders, during grinding, about theaxis .of curvature of the surface to be ground and means forintermittently rotating said headto move said lens holders from stationto station.

16. In a machine for grinding lenses in which the work is subject tocoarse grinding, fine grinding and polishing at successive stationsarranged in a circular series, a combination of grinding tools rotatablymounted at the respective stations and having the desired surface ofcurvature, a rotary head,

work holders carried by said head, means for turning said work holders,during grinding, about the axis of said surface of curvature and meansfor intermittently rotating said head for moving said work holders fromstation to station.

17 In a machine for grinding lenses, cooperating elements comprisingcircular series of work holders and a circular series of grinding tools,a rotary head for support ing the elements of one of said series, commonmeans for oscillating each element of one of said series, means forrotating the elements of the other of said series and means forintermittently rotating said head so as to bring each of the elements ofthe series carried thereby into successive ositions successively withthe elements 0 the other series.

In testimony whereof 30 March 1929 aflix signature.

' JOSEF DESENBERG.

